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ceph: convert ceph_mds_session.s_ref from atomic_t to refcount_t 

refcount_t type and corresponding API should be
used instead of atomic_t when the variable is used as
a reference counter. This allows to avoid accidental
refcounter overflows that might lead to use-after-free
situations.

Signed-off-by: Elena Reshetova <elena.reshetova@intel.com>
Signed-off-by: Hans Liljestrand <ishkamiel@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: David Windsor <dwindsor@gmail.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
This commit is contained in:
Elena Reshetova 2017-03-03 11:15:06 +02:00 committed by Ilya Dryomov
parent d6a3408a77
commit 3997c01d26
2 changed files with 12 additions and 11 deletions
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18
fs/ceph/mds_client.c
View File

@ -378,9 +378,9 @@ const char *ceph_session_state_name(int s)
static struct ceph_mds_session *get_session(struct ceph_mds_session *s)
{
if (atomic_inc_not_zero(&s->s_ref)) {
if (refcount_inc_not_zero(&s->s_ref)) {
dout("mdsc get_session %p %d -> %d\n", s,
atomic_read(&s->s_ref)-1, atomic_read(&s->s_ref));
refcount_read(&s->s_ref)-1, refcount_read(&s->s_ref));
return s;
} else {
dout("mdsc get_session %p 0 -- FAIL", s);
@ -391,8 +391,8 @@ static struct ceph_mds_session *get_session(struct ceph_mds_session *s)
void ceph_put_mds_session(struct ceph_mds_session *s)
{
dout("mdsc put_session %p %d -> %d\n", s,
atomic_read(&s->s_ref), atomic_read(&s->s_ref)-1);
if (atomic_dec_and_test(&s->s_ref)) {
refcount_read(&s->s_ref), refcount_read(&s->s_ref)-1);
if (refcount_dec_and_test(&s->s_ref)) {
if (s->s_auth.authorizer)
ceph_auth_destroy_authorizer(s->s_auth.authorizer);
kfree(s);
@ -411,7 +411,7 @@ struct ceph_mds_session *__ceph_lookup_mds_session(struct ceph_mds_client *mdsc,
return NULL;
session = mdsc->sessions[mds];
dout("lookup_mds_session %p %d\n", session,
atomic_read(&session->s_ref));
refcount_read(&session->s_ref));
get_session(session);
return session;
}
@ -466,7 +466,7 @@ static struct ceph_mds_session *register_session(struct ceph_mds_client *mdsc,
INIT_LIST_HEAD(&s->s_caps);
s->s_nr_caps = 0;
s->s_trim_caps = 0;
atomic_set(&s->s_ref, 1);
refcount_set(&s->s_ref, 1);
INIT_LIST_HEAD(&s->s_waiting);
INIT_LIST_HEAD(&s->s_unsafe);
s->s_num_cap_releases = 0;
@ -494,7 +494,7 @@ static struct ceph_mds_session *register_session(struct ceph_mds_client *mdsc,
}
mdsc->sessions[mds] = s;
atomic_inc(&mdsc->num_sessions);
atomic_inc(&s->s_ref); /* one ref to sessions[], one to caller */
refcount_inc(&s->s_ref); /* one ref to sessions[], one to caller */
ceph_con_open(&s->s_con, CEPH_ENTITY_TYPE_MDS, mds,
ceph_mdsmap_get_addr(mdsc->mdsmap, mds));
@ -3881,7 +3881,7 @@ static struct ceph_connection *con_get(struct ceph_connection *con)
struct ceph_mds_session *s = con->private;
if (get_session(s)) {
dout("mdsc con_get %p ok (%d)\n", s, atomic_read(&s->s_ref));
dout("mdsc con_get %p ok (%d)\n", s, refcount_read(&s->s_ref));
return con;
}
dout("mdsc con_get %p FAIL\n", s);
@ -3892,7 +3892,7 @@ static void con_put(struct ceph_connection *con)
{
struct ceph_mds_session *s = con->private;
dout("mdsc con_put %p (%d)\n", s, atomic_read(&s->s_ref) - 1);
dout("mdsc con_put %p (%d)\n", s, refcount_read(&s->s_ref) - 1);
ceph_put_mds_session(s);
}

5
fs/ceph/mds_client.h
View File

@ -7,6 +7,7 @@
#include <linux/mutex.h>
#include <linux/rbtree.h>
#include <linux/spinlock.h>
#include <linux/refcount.h>
#include <linux/ceph/types.h>
#include <linux/ceph/messenger.h>
@ -156,7 +157,7 @@ struct ceph_mds_session {
unsigned long s_renew_requested; /* last time we sent a renew req */
u64 s_renew_seq;
atomic_t s_ref;
refcount_t s_ref;
struct list_head s_waiting; /* waiting requests */
struct list_head s_unsafe; /* unsafe requests */
};
@ -373,7 +374,7 @@ __ceph_lookup_mds_session(struct ceph_mds_client *, int mds);
static inline struct ceph_mds_session *
ceph_get_mds_session(struct ceph_mds_session *s)
{
atomic_inc(&s->s_ref);
refcount_inc(&s->s_ref);
return s;
}